This invention relates to a multi-function key input device having a liquid crystal display (LCD) unit, in which characters or the like can be clearly displayed even when the device is within a minimum ambient light environment. Different information may be displayed for different operation modes which are specified by operating the input keys.
Heretofore, telephone sets in which telephone numbers have been stored, and whenever calling, the telephone number to be called is displayed and a message is sounded, and electronic devices, such as a terminal unit for an electronic financial computer or an electronic computer which have intelligent functions using magnetic cards, have been devised. Such sets or devices generally provide for a data inputting operation, which is generally carried out by operating a rotary dial or push-buttons. When push-buttons are utilized, they generally partially protrude from a surface of a panel forming a keyboard. Both the dial type data inputting means and the key type data inputting means for multi-function input modes are generally so bulky that it is very difficult to incorporate either of them in a limited narrow space. As a result, such data inputting means are usually located at some distance away from a display unit of the device. It is therefore impossible to detect whether or not the data inputting operation has been correctly carried out unless each manual data inputting operation is confirmed by referring to the display.